Their Trade is Treachery
by Chapman Pincher
Chapman Pincher is about 95, still alive, and has been a thorn in the side of the Establishment throughout his long career as a journalist. In the early 1980s, he published Their Trade is Treachery, in which he alleged that Sir Roger Hollis, who had been the head of MI5, was a Soviet agent. The book caused a great scandal when it was published.